22.106 Neutron Interactions and Applications (Spring 2005) Problem Set No. 7 Due: May 3, 2005 The purpose of this Problem Set is primarily to go through the derivations of a number of key results encountered in the lectures on the theoretical basis underlying thermal neutron scattering and the dynamic structure factor S (k , ω ) . Problem 1 Derive the Born approximation in neutron scattering , Eq. (15.26) in the Lecture Notes, starting with the integral equation approach to potential scattering. Problem 2 Investigate the validity of the Born approximation for thermal neutron scattering to show whether or not the approximation is valid. Problem 3 Give a detailed discussion of what is the Fermi psuedopotential. Why is it useful in thermal neutron scattering? Problem 4 Show the double differential neutron scattering cross section can be expressed in terms of the dynamic structure factor, S (k , ω ) . Discuss briefly why this quantity is useful in the study of structure and dynamics of physical systems. Can S (k , ω ) be calculated using Monte Carlo or Molecular Dynamics simulation?